#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
typedef pair<int, int> PII;

const int N = 2e5 + 10;
const LL mod = 1e9 + 7;

bool cmp(vector<int> &A, vector<int> &B)
{
	if(A.size() != B.size()) return A.size() > B.size();
	for(int i = A.size() - 1; i >= 0; i--)
		if(A[i] != B[i]) return A[i] > B[i];
	return true;
}

vector<int> sub(vector<int> &A, vector<int> &B)
{
	int t = 0;
	vector<int> res;
	for(int i = 0; i < A.size(); i++)
	{
		t = A[i] - t;
		if(i < B.size()) t -= B[i];
		res.push_back((t + 10) % 10);
		if(t < 0) t = 1;
		else t = 0;
	}
	while(res.size() > 1 && res.back() == 0) res.pop_back();
	return res;
}

signed main ()
{
	cin.tie(0), cout.tie(0), ios::sync_with_stdio(0);
	
	string a, b; cin >>a >>b;
	vector<int> A, B;
	for(int i = a.size() - 1; i >= 0; i--) A.push_back(a[i] - '0');
	for(int i = b.size() - 1; i >= 0; i--) B.push_back(b[i] - '0');
	
	if(!cmp(A, B)) swap(A, B), cout <<'-';
	auto res = sub(A, B);
	for(int i = res.size() - 1; i >= 0; i--) cout <<res[i];
	
	return 0;
}